1. Field of the Invention
The field of the invention is woodburning stoves. More particularly the field of the invention is those woodburning stoves which include means for increasing the efficiency of combustion of the wood fuel and transferring heat energy to the heating and cooking surfaces of the stove.
2. Description of the Prior Art
In the past, woodburning stoves were the primary means of heating and cooking in the home. For reasons of convenience, however, woodburning stoves have been replaced by electric stoves and gas ranges. In recent years, woodburning stoves have had a return in popularity, particularly in rural areas where the relative cost of wood is inexpensive compared to the alternative energy sources.
It is, of course, desirable for any stove to operate efficiently. The advantages of fuel efficiency become even more apparent in the context of woodburning stoves, because of the relative inconvenience in having to supply wood to the fire, and because incomplete combustion of a wood fire produces undesirable smoke and soot which is discharged through the exhaust duct of the stove.
The particular advantages involved in the clean burning wood stove are (1) fuel economy, (2) added convenience in having to bring less wood to the fire and in having to tend the fire less often, (3) cleaner exhaust fumes and thus less air polution and (4) to the extent that complete combustion can be controlled, the temperature of the heating and cooking surfaces can also be controlled.
In U.S. Pat. No. 239,517 to Leiter is disclosed a device which aids in more complete combustion in a stove. The Leiter device is an open ended box which fits into the passageway leading to the exhaust duct. As smoke and exhaust gas are forced through perforations in the box, the gases are reheated causing more complete combustion. The Leiter device does not provide a fresh air supply to aid in recombustion.
In U.S. Pat. Nos. 1,172,128 and 1,172,129 to Frost is disclosed the introduction of fresh air through a pipe to discharge above the combustion area in order to provide additional combustion of the fuel particles contained within the exhaust gas. In U.S. Pat. No. 1,153,333 to O'Neill is disclosed a device in which heated air is introduced into the combustion chamber after having been brought through orifices in the cooking surface. In U.S. Pat. No. 1,169,119 to Brewer is disclosed a heating system in which heated air is discharged to both above and below the grate in the combustion area.
U.S. Pat. No. 3,649,211 to Vosper and U.S. Pat. No. 4,078,541 to Roycraft are two modern patents which disclose the injection of secondary air to accomplish secondary combustion of unburned fuel particles. The Vosper patent discloses the injection of air into the exhaust duct of an incinerator. The Roycraft patent discloses a heating furnace that operates on either oil or wood fuel. Pre-heated secondary air is injected to accomplish secondary combustion of the wood particles.